Set deviceScaleFactor on the renderer WebView to enable scaling when not in fixed-layout mode.

content/renderer/render_view_impl.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/renderer/render_view_impl.h"
 
 #include <algorithm>
 #include <cmath>
 #include <string>
 #include <vector>
@@ skipping 2705 matching lines @@
     std::string str =
         command_line.GetSwitchValueASCII(switches::kEnableFixedLayout);
     std::vector<std::string> tokens;
     base::SplitString(str, ',', &tokens);
     if (tokens.size() == 2) {
       int width, height;
       if (base::StringToInt(tokens[0], &width) &&
           base::StringToInt(tokens[1], &height))
         webview()->setFixedLayoutSize(WebSize(width,height));
     }
+  } else {
+    int device_scale = webkit_preferences_.default_device_scale_factor;
+    webview()->setDeviceScaleFactor(device_scale);
+    webview()->setPageScaleFactorLimits(1, WebKit::WebView::maxPageScaleFactor);
   }
 }
 
 void RenderViewImpl::didStartProvisionalLoad(WebFrame* frame) {
   WebDataSource* ds = frame->provisionalDataSource();
   DocumentState* document_state = DocumentState::FromDataSource(ds);
 
   // Update the request time if WebKit has better knowledge of it.
   if (document_state->request_time().is_null()) {
     double event_time = ds->triggeringEventTime();
@@ skipping 2585 matching lines @@
 bool RenderViewImpl::WebWidgetHandlesCompositorScheduling() const {
   return !!RenderThreadImpl::current()->compositor_thread();
 }
 
 void RenderViewImpl::OnJavaBridgeInit() {
   DCHECK(!java_bridge_dispatcher_);
 #if defined(ENABLE_JAVA_BRIDGE)
   java_bridge_dispatcher_ = new JavaBridgeDispatcher(this);
 #endif
 }